Osburn runaway?

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Now if it's hard to control the draft, what can I do to slow down the rate of burn?
Get a Cat stove if you want a slow burn. Non-cat stoves are designed to burn hot and then slowly drop in temp over the course of the burn cycle.
 
cygnus said:
Hi Bagelboy.

I think 600 degrees on the top of an insert is a problem. That is not actually the stove top. That's the temp of the air jacket running around the stove. The stove is MUCH hotter.
Since there really is no good area to monitor the stove top temp, I have a thermo stuck in the air outlet. This is just gives me a relative temp to work with. I can't contribute to those, "I gone her cruis'in at 600 stove top" conversations because I have no idea what the actual stove top temp is but, I know that I'm crus'in when the output air is 175-225. At 150, the stove is cold and at 350+ I have a problem. I did buy a probe to install in the liner but I don't think I'll ever put it in. This seems to working OK.

I experienced many overfires in my Osburn with the 30' insulated liner. It defies logic but, the air control only regulates the amount air to the secondaries. The primary is an open, uncontrolled hole. In my opinion this is a design flaw since it performs so terribly with a strong draft. My primary was sucking WAY TOO MUCH air due to a very strong draft and I was burning through huge quantities of wood. Once I found and obstructed the primary air intake I discovered what using a stove was supposed to be like all along. I can easily get 6 hours burns with half the wood. There is a promised land. Did you ever find the primary intake from this thread? https://www.hearth.com/talk/bookmarks/?type=post&id=1557168

Did you completely seal the hole or partially?

Only partially. I tried a magnet first and obstructed it about 3/4. I could barely keep a fire lit. Imagine going from a setup that would over fire in a heartbeat to something that doesn't stay lit. That was an Ah Ha! Moment! The factory opening is .4". And I'm sure thats fine for the Florida bungalow with a 8' stack in the summertime but not in the northwest with a 30 footer. I've been drilling out plugs and testing. First tried a .25" but that was a bit small. Running .3125 now and seems about right... Maybe just a hair oversized.
 
Cyngus, I placed a bolt underneath where the hole is when the air is cut off all the way. I think that is what your talking about. When you say .3125 plugs, what do you mean? Do you have a pic?
 
Let me try to explain what I've done and discovered a bit clearer. I can't get pics now.

First, understand that I'm running the Osburn 2200 so the 2400 may be different.

Yo access or view the air inlets, you need to remove the piece of duct that funnels air off of the fan. Just two screws, one on each side. Use a small mirror to get a view underneath once the duct is removed.

On the 2200, the only air control is a slide on the right side that travels over a triangular cutout on the underside of the firebox. This controls the secondary air. The slide has a travel of about 3-4" so the cutout is that long and is about 3" from the bottom-front edge of the firebox.

In between the front edge and secondary cutout is a single, round hole. I've found that this is the primary air inlet and is completely unregulated and not adjustable. It measures .40" in diameter so I found a stubby tap to fit under there and I tapped it with 1/4" NPT threads. Now, I can screw in a brass fitting that I've drilled a smaller hole in. I'm just using something like this: http://shop.hoseandfittings.com/catalog/Fitting/Brass/Pipe/Plug_-_Hex_Head.html and have found a 5/16" hole to offer enough primary air and give lots of control over the fire.

So I've effectively replaced the .4" diameter primary air inlet with a .3125" (5/16") air inlet. That reduces the area if the port by more than half. And I'll say that looking back, I believe it's possible the primary inlet was allowing twice as much air as it really should have. Maybe the Osburn was designed for a 15' stack instead of my 30 footer...seems logical.

Bagelboy - I'm not sure what you mean about the bolt. If you filled the primary inlet with a bolt and completely closed off that hole then I doubt you could really keep a fire lit. I know I had a VERY hard time with the hole obstructed about 80%.
 
Cygnus, the hole you describe is also on the 2400 insert. This is the hole inwhich I am also talking about. I put a bolt in this hole, tightened it down, and have noticed a big difference in the control of air coming in when the air control is pushed in. It does not shut the fire down completely, but it does seem to stop the runaway fires I was experiencing. The only thing is, if the bolt is now blocking this hole, how else is air entering the unit?
 
There appears to be little difference between the Osburn 2400 insert and the freestanding stove. Both seem to have the same top plate. 600 degrees on the stove top of a steel stove is not a big deal, nor is it alarming.

I would spend less time trying to restrict the stove and more time learning how to burn it properly.
 
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Additionally, the 2000 barely sticks out of the fireplace, meanwhile 2400 sticks out of the fireplace much further and you will read higher stove top temps on the 2400 than you would on the 2000.
 
600 degs is not a problem at all on the 2400 to reduce air flow to much is a bigger problem the the stove hitting 800 degs. the stove wants to get up to 500-600 before you shut it down this will insure you will have a clean burn threw out the burn cycle. the stove air control will never shut the stove off it will only slow it down. by reducing your airflow to much you have a better chance to form creosote, in turn a greater likely hood for a chimney fire.

How long of a burn time are you getting on a full load of wood?
 
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Cygnus, the hole you describe is also on the 2400 insert. This is the hole inwhich I am also talking about. I put a bolt in this hole, tightened it down, and have noticed a big difference in the control of air coming in when the air control is pushed in. It does not shut the fire down completely, but it does seem to stop the runaway fires I was experiencing. The only thing is, if the bolt is now blocking this hole, how else is air entering the unit?

Ah, OK. Control was the big thing for me. I really had very little control before my mod. Sounds like you are making progress. I was on year 3 when I figured this out so you have me beat :)

Even with the air control shut down completely there is still air coming through to the secondaries. The plate that obstructs the cutout is not a very tight fit. But, with the primary air obstructed, see how hot you can get the stove. It may not be hot enough. From my experiments the air coming down on the fire from the secondaries didn't keep the fire running hot enough. Stove temps were quite low and I saw very little secondary burning at the top of the firebox. At this point I'm of the thinking that the stove should run hot, and an overfire is always possible under the right conditions (hot coals, wood orientation, wood moisture, timing of air shutdown, etc) just not an expectation on every burn or quite so easy to achieve.

Otherwise, I don't know if there are other air inlets. I wish I had examined the stove a bit more before the install.


Where is Fyrebug to shed some light on this topic?
 
I could be wrong, having a Jotul 8 stove for over 20 years, but to me a runaway fire is one inwhich my firebox goes from 300 degrees to 650 with the air shut down, flames ingulfing the entire firebox. Granted, the Jotul is a cat firebox, and not having bought a new firebox in 22 years, perhaps things have changed somewhat, but I still use the Jotul during the season and control the rate of burn. Like I said, I may be a little behind on the current EPA stoves, but it's hard to believe that a box cannot be controlled and that once filled, it's out of my hands. Let me say Brownbar, I am not being sarcastic or disrespectful in my tone, in fact, I am here to educate myself and get feedback from you and others and appreciate the input!
 
I could be wrong, having a Jotul 8 stove for over 20 years, but to me a runaway fire is one inwhich my firebox goes from 300 degrees to 650 with the air shut down, flames ingulfing the entire firebox. Granted, the Jotul is a cat firebox, and not having bought a new firebox in 22 years, perhaps things have changed somewhat, but I still use the Jotul during the season and control the rate of burn. Like I said, I may be a little behind on the current EPA stoves, but it's hard to believe that a box cannot be controlled and that once filled, it's out of my hands. Let me say Brownbar, I am not being sarcastic or disrespectful in my tone, in fact, I am here to educate myself and get feedback from you and others and appreciate the input!
Before you start modifying the stove, spend more time with it. Every winter there are many threads created about "my stove is running away from me", when in actuality, the stove is operating correctly and it is user error or user expectations.

600 degrees is no where near a runaway. That is its prime operating temperature. You reloaded the stove when it was 400 degrees. This has the tendency to make a stove shoot up in temp quickly. When doing this, you should plan accordingly.

Start to worry when the stove gets above 750. But, even then, the stove will most likely settle.

If you start modifying the stove before you understand how it should actually run, you will only create problems for yourself in the future. I ran a pre-EPA Vigilant for a few years. There is a huge difference between a pre-EPA stove and a modern stove. Modern stoves are designed so you can not completely shut them down. This is done so for a variety of reasons. Once you learn more about your stove, maybe you will decide to restrict the secondary air to alter the burn. But, doing so now, will only cause you to try to run a modern stove like a pre-EPA stove, and odds are it will be a bit of a mess.

Modern Stove Burning or: How I Learned to Stop Worrying and Love A Hot Stove
 
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One thing to consider is a cat stove and tube burner will look different with the air shut down the cat will look like the fire is going out and with a tube burner (your osburn) will still have a fire in it it could take some time for the fire to slow down this will all depend on draft outside temps wood quality and how much fuel you have in the firebox. there is nothing to worry about at 600 deg!
 
No question, I need more time with this new stove. I knew the first year would be a big learning curve. With my other stove, the Jotul, I was told many years ago to keep a flame going at all times, even a small one, and this would cut down on creosote. I ran that stove like that year in, year out. When I would clean it twice a year, very little accumulated in the pipes, just flakes. Never any problems, but you could shut it down immediately if needed. It can be unnerving watching a new stove climb, and climb, engulfed with flames, and not be able to respond.
 
You're fine. There is no need to even think twice about over firing until you see 800+ stove top temps. It's a large metal box full of fuel, it is going to get hotter than your kitchen oven. Enjoy it.

I love seeing my stove cruise between 650 and 750 during the peak of the burn cycle. That means it's working.
 
Hopefully this is helpful: The Osburn 2400i is designed to burn hot. Shutting down the air intake in the front of the unit, as designed, without modifications, on a full load of wood on a large bed of coals will usually increase the stove top temps. This is what a user wants to happen. If you do not want your stove to burn hot load less wood on a smaller coal bed.

Stove top readings on this insert are generally pretty accurate as the jacket can be set several inches back from the front of the stove top.

As others have said, stove top readings of 600-750 are normal for this unit. It's a beast. And this is normal operating temp range for this unit. Enjoy the heat. Don't fear it. Hold off on modifications until you fully understand the unit as originally engineered.
 
Instead of modifying the unit consider modifying burning habits and methods. Experiment with north south burning vs east west. Play around with various species of wood and split size. These modifications in technique can greatly effect your burn cycle and heat output.

If higher stove temps scare you try raking the coals forward, create a small valley or tunnel in the ash and coals, then load a large split or round on the ash in the back place medium or smaller split on the coal bed, the place a few more larger splits tightly packed east west. This should burn pretty slow and temps tend to climb a bit slower. Good luck!
 
image.jpg This is my insert, with the air control closed all the way, and the bolt I installed into the air hole opening. It is under control, and I don't have a runaway firebox. Prior to this, this box would be lit up!
 
image.jpg Here is another. Stove is at 450 degrees. I have blocked off the air hole next to the air control, and the air control is shut down. If I didn't block off the hole next to the air control, this baby would be crying. Make that screaming,
 
It can be unnerving watching a new stove climb, and climb, engulfed with flames, and not be able to respond.
Okay, I'm convinced that Bagelboy has a control problem whether you call it runaway or not. If I couldn't stop a climb in a reasonable amount of time, it would be a problem for me. As I recall, his flue is around 30 feet and he probably needs something to help control draft. If you can't add a damper, then controlling air intake is the only other option left.

True, the temps reached so far are not too alarming, but I know I'd like a little more control.
 
Okay, I'm convinced that Bagelboy has a control problem whether you call it runaway or not. If I couldn't stop a climb in a reasonable amount of time, it would be a problem for me. As I recall, his flue is around 30 feet and he probably needs something to help control draft. If you can't add a damper, then controlling air intake is the only other option left.
I do not see where Bagelboy has a problem. If he was topping out at 700-800 degrees everytime, sure, you might have something. But 600 is at the lower end of a good burn temp.

True, the temps reached so far are not too alarming, but I know I'd like a little more control.
That's not how non-cat stoves work.
 
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View attachment 118172 Here is another. Stove is at 450 degrees. I have blocked off the air hole next to the air control, and the air control is shut down. If I didn't block off the hole next to the air control, this baby would be crying. Make that screaming,
450 seems low. You should be between 550-650 for the most part. That isn't screaming. That is normal.

Like I said earlier, load it and run it. See how it runs. See what you are doing and what the stove is doing. Do this before you start messing with the air holes. If the stove continues to climb far beyond 650 (700-800) don't freak out. Let it burn. Then, after the burn cycle, check the gaskets to be sure you have good seals.

Right now, nothing indicates that your stove is burning out of control.
 
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View attachment 118170 This is my insert, with the air control closed all the way, and the bolt I installed into the air hole opening. It is under control, and I don't have a runaway firebox. Prior to this, this box would be lit up!

I completely agree with BBar and others here. Your pic is not showing anything. That is a tiny, shoulder season fire. The stove can and should be run higher. Learn how to load a stove properly and how to close the air down in steps that your stove top temp settles between 600 and 700 F before messing with the stove's design. If you keep it running at those low temps I am at least hoping you are cleaning your flue regularly.
 
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That's not how non-cat stoves work
I only know it's the way mine works. I'm not after an argument or anything, and I'm the first to admit my limited experience, but I'm used to being able to fairly quickly stop any temperature rise that I'm experiencing at any temperature I want. I've always been able to do that and I've done it over a wide range of situations. I can control the temp of my stove at any temperature that I choose regardless of the load. If I want to stop my temps at 300, I can. But he can't. I just know that I'd be very uncomfortable if I couldn't.

The maximum temps that the OP has been experiencing so far have been moderate, but that's been with only a very small load because he's been afraid to load it up.

I don't like the idea of messing with air controls. But I can understand his concern. With greater than 30' of flue, his draft must be pretty strong and I'd be a bit concerned about loading to the gills, too.
 
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